Swimming costume, swimsuit, swimwear, trunks, bathing | WordReference Forums
Australians might say "swimmies" in BrE we just say trunks (for men) if it's clear from the context wha you mean and "costume" for women ... Image entries on Google "swimming costume"----> 947 "swim costume"----->2.970 "swim suit" >103.000 "swimming ......